Control mechanism



Dec. 15, 1931. w. ERNST CONTROL MECHANISM FOR HYDRAUL IC PRESSES Original Filed Dec. 8, 1926 3 Sheets-Sheet 1 Dec. 15, 1931. w. ERNST I CONTROL MECHANISM FOR HYDRAULIC PRESSES Original Filed Dec. 8, 1926 3 Sheets-Sheet 2' 9 wk MW l W. RN m 3 5 a n a W rl'rrzsZ inventor (IttornegS.

Dec. 15, 1931. ERN T 7 Re. 18,287

CONTROL MECHANISM FOR HYDRAULIC PRES SE3 Original Filed Dec. 8, 1926 3 Sheets-Sheet J" y E I lmoenkor Gttoruegs.

Reiuued Dec. 15, 1931 UNITED STATES A Re. 18 287 PATENT OFFICE WALTER ERNST, OF HOUR!" GILELD, OHIO, ASSIGNOB TO THE HYDRAULIC PRESS m- UFAGIUBING mm, 0] MOUNT GILEAID, OHIO CX JRTBOL IECHLNIBI I03 HYDRAULIC PBESSES on mnno. 1,711,:70, emu a ru so, 1920, Briallfo. 153,410, fled lieuember a, me. Application mreilsue filed luck The invention herein disclosed isllparticularl adapted for usewith a hydra 1c press of t e character disclosed in my Patent No. 1,67 2,561, issued June 5, 1928, but is adapted v I for use with other types of presses.

' It is common to em by in hydraulicpress mechanism a pump or forcing fluid under pressure to said press, which pump isof the type knownas a variable stroke, variable and reversible discharge. A pump of this character may be seen for example in Patent 1,250,170 to Hele-Shaw et al., and is well known to those familiar with this art. In such pumps-the direction of movement of the liquid dischargedmay be reversed and the speed may be varied slmply by reciprocating a cross head or control member from one po- 1 sition to another. This cross headvis connected to a floating ring which may be shifted ofi center with relation to other elements of the pe imp or maybe held in a central position.

hen in a central position the pump runs idly while when the floating ring'is ofi center on one side the fluid under pressure will be discharged in one direction but in the opposite direction when the floating ring is moved 01f center on'the other side.

It is unnecessary to set forth the specific construction of thepump in any more detail and the same is not illustrated herein since the present invention relates to control mechanism inter osedbe'twe'en' the pump and the press where y the operation of the pump will be controlled as desired.

Assuming that the press is idle and that the pump is running idly a movement of the leveradjacent the pressthrough the interposed control mechanism will cause the pump to'deliver fluid under pressure and produce the pressing stroke of the platen of the press. When a certain'resistance has beenbuilt up in the system the control mechanism will operate automatically-to throw the pump into reverse and produce the return movement of the press platen. When this return movement is completed the control mechanism will be again operated to terminate the return.

stroke of the platen, the latter remaining in its idle' position until another pressing opera.- tion is initiated manually.

14, 1981. Serial 1'0. 528,710.

In the drawings:

Figure 1 is a v1ew showing a elevation; and a press, and control li perspective. I

Figure2 is a view of a detail. V Figure 3 is a longitudinal section through a part of the control mechanism.

Figure 4 is a diagrammatic view of the hydraulic circuit.

The press is herein ing a bed A and a top B connected by four agem illustrated as comprisstrain rods C and having the usual table and.-

cooperating'asliding platen D operated by a mam ram which 1s mounted for reciprocation in a-main cylinder E formed with the usual ram-advancin chamber. The press is also rovided with ooste'r rams H connected to t e platen and arranged to operate in booster cylinders H, and with push-back rams-I connected to the pater; and arranged to operate in push-bac cylinders I, the push-back cylinders being pie'ovided with the usual ram-returning cham rs. 'It is For the pur oses of illustration one-form to be understood that this showing is merely illus-' trative and that various types of; resses may of control mec anism embodyingthe inven- J tion will be described as being used for con-g trolling the operation of a press of the kind disclosed by 'my Patent No. 1,672,561, referred to above. V p

A pipe line a is shown as leading from the pump and has a branch b which communicates with the booster cylinders "H which are intended to initiate the movement of the press ram. This line also has a connection 0 leading to a valve mechanism generally indicated at d. From this valve mechanism a pipe e comrimnioates with the main cylinder E above the press ram. From the upper art of this cylinder a pipe f commumcatesy the way of a valve mechanism indicated generally at 9 witha surge tank h, which has a pipe 5 communicating with vthe --valve mechanism d.

. A second pipe 7' leads irom the pump 'G and has a separate branch k communicatin ,with the two push-back cylinders 'I' "whi similar ably mounted in the'partitions 1' and t and set to open at di 140 plurality openings 8.

with a small chamber underlyin the stem of the valve mounted in the vafve mechanism 9 above mentioned. The pipe j also communicates with the valve mechanism (1.

The valve mechanism dwzomprises a main.

casting m which is divided into four chambers n; 0, p and g. A partition '1' between the chambers n and 0 is provided with a of passages 8 and a-partition t bechambers o and p is provided with passages u. A valve stem '0 is slidtween the carries at one end a head w lying in the chamber p and is adapted to close the openings u and at its other end a head as lyin in the chamber n is The valve stem is of such length that when one set of openings is closed the other is opened.

Also slidably mounted in the casing is a valve 3 which coacts with a valve seat a to control communication between the chambers n andg. The upper end of this valve stem is guided in a bushing a set in the cas ing m and acting to retain a packing b. The lower end of the valve stem as a packing 0' held in place by a cylindrical member d which is screwed into the.casing m. This member (1' has mounted therein a coil spring e, which bears at one end against the valve stem and at its other end against a plate f, the position of which may be adjusted by a screw g adjustably mounted in a cap it which is screw threaded on the open end of the member d. In this manner the tension of the spring may be varied and the valve ering pressures.

The valve; mechanism gfcomprises a casing 71' having therein a passage j which is controlled by a valve 7:. The stem Z of this valve is separate and fits slidably in a short tubular member which is connected to the end of the pipe Z. Suitable packing m is provided and a small chamber 12/ is formed in the tubular member just mentioned. A coil spring 0 surrounds the valve stem 1' and bears at its lower end against a collar 12 carried by said valve stem and at its upper end against a fixed collar g through which the valve stem Z tends to hold the stem Z The operation of the scribed as follows. It is assumed that it is desired to operate the press. The pump is in its lower position.

- set to deliver fluid under pressure through the line a. The branch 0 of this line which communicates with the chamber n will 'thus' receive fluid under pressure and the 'valve stem '0 will slide to the right in Figure 4 so that the valve head a: closes communication between the chambers n and o as shown in this figure. At the same time, fluid under pressure will pass through the branch pipe adapted to close the b the main cylinder E,

slides so that this spring.

circuit may be de-- line 'b to the booster cylinders H and 'thusstart the movement of the press ram downwardly. This, of course, tends to produce avacuumin the upper portion of the main 0' linder E, but the suction exerted through t e pipe f will lift the valve k oif its seat against the force of gravity and permit liquid to flow from the surge tank It through the valve casing 11' portion of the main cylinder E behind the press ram. This action will continue until the ram meets suflicient resistance to build up the pressure in the pipe line a to a point where it is sufiicient to overcome the force of the spring e. The valve y will then be moved downwardly away from the valve seat pipe 0 through the chamber n, chamber 9, and pipe e'into the main cylinder E. As soon asthe fluid under high pressure enters exerted through the pipe f will close the valve is and prevent this fluid from returning to the surge tank at this time. The parts will remain in this position until the pressing operation is completed.

Thereafter, the pump will be reversed in a manner to be later described and will discharge fluid under pressure into the pipe line 7'. The branch k of this line will conduct fluid to the push back cylinders I and immeand pipe f into the upper g 2, opening communication between the chamers n and g and the fluid will pass from the the back pressure diately begin returning the ram to its nor- ,valve casing i into the surge tank It. As soon as the press ram reaches its upper normal position, its movement. will be arrested as will be later described.

It will be understood that the particular arrangement of press and operating valves described above is fully shown, described pass through the branch I of the valve stem Z and exand claimed in my Patent N 0. 1,672,561, and

does not, per se, terof the present to novel control mechanism and the operatiVe connection of ous presses and hydraulic circuits.

This control mechanism comprises carried by the press: referred to broadly as elements preferably frame which may be constitute the subject mat: invention, which is directed suchmechanism to vari the controlling linkage and control rsena nism which may be carried by or'attajcheif to the pump proper andconstitutesjthe control mechanism proper. I a The control linkage comprises a handle'l carried by the press frame and normally held in intermediate position b springs 2 and 3.

to an arm 6 havin a hub 7 which is loosely mounted on a sha t -8 carried by the press frame. A collar 9 is fast on said shaft and the hubs 7 and 9 have interlocking projections cutaway as indicated at 10 to provide for a certain amount of lost motion in either direction of one part relative to the other.

, An arm 11 is fixed to the shaft 8 and is connected by a link 12 which is preferably adjustable to an arm 13 of the control mechanism proper. The shaft 8 also has an arm 14' provided with a forked end which overlies a head 15 on a rod 16 mounted to slide in a bracket 17 carried by the press and provided with an adjustable stop collar 18 adapted to be engaged by an arm 19 which terminates in an eye sliding on the rod 16 which arm is carried by-the platen D and will engage the stop collar 18 at a point predetermined by the adjustment of said stop collar.

If the parts are in the position shown in Figure l and the lever 1 is depressed the linkv 5 will be raised and the arm 6 moved upwardly, which after the lost motion is taken up, will produce a movement of the rod 8 and through the arm 11 and link 12 will move the control lever 13 in the direction of the arrow (1 and cause the pump to deliver fluid in a properdirection to initiate the pressing operation. At the termination of the downward movement of the press, the control mechanism indicated generally at F and carried by the pump G will operate to move the rod 12 as hereinafter described quickly toward the right. This will not be dangerous to the operator because this movement will merely take up the lost motion and cause no movement whatever of the lever- 1 at this time, since this lever has already been released by the operator and has been returned to its central position.

When the control mechanism as just described has been reversed, the pump then delivers fluid under pressure in a direction to return the platen -D to its upper position. 0 In this upward movement the arm 19 will ultimately contact with the collar 18 which p which the pump remains idle.

The control mechanism F through which the above sequence of operations is produced will now be described. The pump is pro-' vided with the usual control member or movable cross head 20 and. attached thereto is astem 21. This stem is mounted to slide in a sleeve 22, which is hollow throughout a portion of its length, and the head 23 of the stem bears against a spring 24 enclosed in the hollowed portion of the sleeve 22. A stem 25 is screw threaded into the sleeve 22 and the casing of the control mechanism and is connected as at 27 to the stem 25. The free end of the lever 13 is provided with a hardened portion28 which is adapted to engage with a detent or trip member 29 which is fulcrumed at-30. A strong spring 31 is coiled about the sleeve 22 and bears at one end againsta fixed part and at the other against a flange on said sleeve and obviously tends to move the sleeve and the stem 25 toward the left as shown in Figure 3. This movement when permitted is limited by the engagement of a collar 31 on the stem with an adjustable stop member 32. v

The fulcrum 30 of the'trip 29 is connected to a small cylinder 30' which travels horizon-' tally on slides on top of a control member F. This cylinder may be moved and locked in cylinder. From this chamber a pipe 36 com-- municates with the main cylinder of the press so that the pressure in the chamber 35 will always be the same as that in the main press cylinder. A spring 37 bears at one end against the trip 29 and tends to hold it in engagement with the free end 28 of the control lever 13 as shown in Figure 3. The tension of this spring 37 may be adjusted by means of a hand wheel 39 carried by a flange 38 o the cylinder 30'.

Assuming that the press is in its upper position, the operator initiates the operation by moving the hand lever 1 as above described which moves the link 12 toward the left and rocks the control lever 13 about its pivot point 26 thereby moving the .free end-thereof toward the right. This movement will cause the upper end thereof to cam the trip 29 out of its path after which said trip" snaps into .the Figure 3 position andholds the control lever 13 in that position.

This movement of the control lever toward the right also moves the cross head 20 and so controls the pump that fluid will be delivered under pressure to the main press cylinder. The spring 24 per-.

mits a little overtravel of the stem 25 after the stem 21 has completed its stroke in order that the free end '28 may move far enough to insure its being retained by the trip 29. The amount of movement of the lever 13 and the stem 2g5 will begoverned by the position of thetrip member 29. If the fulcrum 30 is moved by means of the hand wheel 41 toward the left the trip 29 will engage the control lever 13 at an earlier point of its movement so. that the stem 25. will be moved only through a part of its full stroke which will result in the pump delivering only a partial amount of the fluid and therefore impa'rtin slower speed to the press. This handwhee 41 may be set for any speed desired. Since fluid is now being'delivered undo the desired pressure to the main cylinder of the press, the press platen will now move until it hits a certain resistance; The pressure in the system and consequently in the stem to move toward the left a suflicientdistance to reverse'the pump and cause fluid to be discharged under pressure to the press for returning the platen to its normal position. The amount of this movement and consequently the return speed of the press giay be regulated by adjusting the stop mem- The press will now return at this predeter-' mined rate of speed until the arm 19 contacts with the stop 18 as above described which 'will impart a movement to the control arm 13 returning the stem 21 to the right and moving the pump into neutral position.

The

parts will remain in such position until asecond sequence of operations is initiated by cross head is set for a movement of the lever 1. The press will stay in upper position indefinitely so long as the pump is running even if there is a leak in the system, since as soon as it starts to move downward it will release the stop collar 18 thus releasing the controlling lever 13 and permitting the spring 31 to move the stem.

'21 slightly, thus moving the pump to a position to exert a certain pressure in a direction to return the platen to its upper position.

It will be observed that the lever 13 constitutes a device movable to three'positions, in the first of which the pump cross head is set in its neutral position, in the second of which the cross head is set for limp delivery in a direction to cause the platen to perform a pressing stroke, and in the third of which the pump discharge in a direction to cause the platen to perform a re turn stroke. The manually operable lever 1 and the associated linkage serves to move the lever 13 to its second position in which it will be retained by the trip 29; and the spring 31, whose action is controlled by the pressure responsive trip 29 and piston 34, serves to move the lever from its second position to its third position.

' It may be noted that if the fulcrum point 'by the scope of the duce the return 30 is moved to the extreme-right, the automatic feature may be eliminated since in this case the tri 29 will never engage with the lever 13 and the press will operate like an ordinary manually operated double acting cylinder. It is also noted that the trip 29 may be provided with a hand lever 40 through which it may be operated independently of the automatic mechanism if desired. It is also possible to operate the lever 1 by means of a pedal instead of by hand. Various other detail changes may be made in the precise construction without in any way departing from the spirit of the invention, which is to be regarded as limited only appended claims. I claim as my invention: 1.' A control mechanism adapted to be operatively connected to a hydraulic circuit inposition to cause the pump to discharge so as to produce the pressing movement of the platen, pressure controlled means for thereafter moving the device from the second to the third position to reverse the discharge of the pump and produce the'return movement of the platen, and automatic means for thereafter moving the device from the third to the first position to place the pump in a neutral position.

2. A control mechanism adapted to be operatively connected to a hydraulic circuit including a reversible variable discharge pump and a hydraulic press having a;movable platen; said mechanism comprising a device adapted to occupy three positions, means for movmgthe device from the-first to the second position to bring about the pressing movement of the platen, means for detaining V to produce the return movement of the platen.

3. A control mechanism adapted to be operatively connected to a hydraulic circuit including a reversible variable discharge pump and a'hydraulic press having a movable platen; said mechanism comprising a device adapted to occupy three positions, means for moving the device from the first to the second position to bring about the pressing movement of the platen, a spring actuated detent for detaining the device in such position, means controlled by the pressure in the circuit for releasing said detent and spring means for moving said device when released from the detaining means from the second to the third position to promovement of the platen.

"4. A control mechanismadapted to be op- ,eratively connected to a hydraulic circuit inposition to bring about the pressin movement of the platen, a spring actuate detent for detaining the device in such position,

means for varying the normal position of the detent to thereby vary the position of the i device'and the conseguent speed of the press,

and means controll by the pressure in the circuit for releasing said detent to permit the device to move to another posltion.

5. A control mechanism adapted to be operatively connected to a hydraulic circuit in.-

cludin a reversible variable discharge; pulmpf e p atand a ydraulic press having amova on; said mechamsm comprlslng a devlce adapted to occupy three ositions, means for moving the device from t e first to the second position to bring about the pressing movement of the platen, means for detaining the device in such position, means controlled by the pressure in the circuit for releasing the device from the detaining means, means for moving the device when released from the second to the third position, and means for varying the third position of the device and the consequent speed of the return movement of the platen.

' 6. A control mechanism" adapted to be operatively connected to a hydraulic circuit including a reversible variable discharge pump and a hydraulic press having a movable platen; said mechanism'comprising a device adapted to occupy three positions, means for moving the device from the first to the second position to bring about the pressing movement of the platen, means for detaining the device insuch position, means for varying the normal position of the detainin means to thereby vary the position of sai device andthe consequent speed of the platen, means controlled by the pressure in the circuit for releasing the device from the detaining means, means for moving the device when released from the second to the third position,

and means for varying the third position of the device and the consequent speed of the return movement of the platen.

' 7. A control mechanism adapted to be op-' eratively connected to a hydraulic circuit including a reversible variable discharge pump and a hydraulic press having a movable platen; said mechanism comprising a device movable to .three positions, manually operable means adjacent said ress for moving the device from the first to t e second position ,to bring about the pressin' movement of the platen, means controlled y the pressure in the circuit for moving the device from the I second to'the third position to produce the the return movement 0 cluding a reversible variable discharge pum and a hydraulic press having a movab e platen; said mechanism. comprising a device movable to three positions, manually opera- 1 b'le means adjacent said press for moving the device from the first'to the second position to bring about the pressing movement of the platen, means; controlled the pressure in the circuit for moving the evice from the second to the thirdt'position to produce the platen, means controlled by the return movement of the platen for moving the device from the third to the first'position to place the pump in a neutral position, and means for varying the second and third positions of said device.

9. A control mechanism adapted to be operatively connected to a hydraulic circuit including a reversible variable discharge pump having a control member and a hydraulic press having a movable platen; said mechanism comprising a movable device connected to said control member, means for moving said device to a position to produce the pressing movement of the platen, a spring sure in the circuit for releasing said detent, and means for thereafter moving said device to a position to produce the return movement of the platen.

10. A control mechanism adapted to be operatively connected to a hydraulic circuit 1 operated detent for said device, a piston connected to the detent and operated by the presincluding a reversible variable discharge pump having a control member and a h draulic press having a movable platen; said mechanlsm comprising a movable device connected to said control member, means for minedpressure at which the detent will be' released.

11. A control mechanism adapted to beoperatively connected to a hydraulic circuit including a reversible variable discharge pump having a control1 member and a h draulic press having a movable platen; said mechanism comprising a movable device connected to said control member, means for moving said device to a position to produce the pressing movement of the platen, a spring operated detent forsaid device, a piston connected to the detent and o erated by the pressure in the circuit for re easing said detent,

' moving means for varying the predetermined pressure at which the detent will be released, and means for thereafter moving said device to a position to produce the return movement of the platen.

12. A control mechanism adapted to be operatively connected to a h draulic circuit including a reversible variable discharge,

pump and a hydraulic press having a movable platen; said 'mechamsm comprising a lever adapted to be connected to and control said pump, a link extending from the lever to a point adjacent the press, a rock shaft connected to said link,- and manually operable lever-actuating means having a lost motion connection with said rock shaft.

13. A control'mechanism adapted to be operatively connected to a hydraulic circuit including a reversible var1able discharge pump and a hydraulic press having a movable platen; said mechanism comprlsmg a lever adapted to be connected to and control said pump, a link extending from the lever to a point adjacent the press, a rock shaft connected to said link, manually operable lever actuating means having a lost motion connection with said rock shaft, and-means adapted to be operated by. the movement 0f the platen having a one way connection with the rock shaft for. moving the lever to neutral position. 5

i 14. In combination, a reversible, variable capacity pump; a double acting hydraulic motor, means formin with the pump and motor a hydraulic circuit, mechanism for varying the. pum capacity from zero in either direction -0 flow, means for moving said mechanism from zero capacity position to pumping position whereby the motor piston is made to advance, means res on-sive to the attainment of a predetermine pressure on the motor piston for reversing said mechanism whereb the piston is made to perform a return stro e, and meansresponsive to the attainment by the piston of a redetermined position in the .return stro e for said mechanism to zero capacity position.

15.- The combination with a hydraulic press including a stationary table and a reciprocatory p aten movable towards and from the table, of a reversible pump, means forming with the press and pump a hydraulic I circuit, and controlhng means operativel connected with the ump and circuit for e fecting movement 0 the platen towards the table and responsive to the pressure built up in the circuit during said movement 'of the platen for automatically reversing the pump and platen irrespective of the position of the platen relative to the table.

16. The combination with a hydraulic press including a stationary table and a reciprocatory platen movin towards and from the table, of a reversib e pump, means forming 'from the table,

forming with the press and pump a hydrau-.

' from the table and including a control lever operatively connected with the ump for controlling the direction of fluid iibw in the Eircui t, a trip for holding said extreme position for. directing the fluid to move the platen towards the table, means responsive to the built up pressure in the circuit during said movement of the platen to release said trip, and means for moving the control lever to tion upon release of said trip whereby the direction of fluid flow in the circuit will be reversed.

17. The combination with a hydraulic press including a stationary table and a reciprocatory platen movable towards and of a reversible pump, means lic circuit, and controlling means operativel connected with the pump and circuit for e fecting movement 0 the platen towards and from the table and includinga -control lever operatively connected with the ump for controlling the direction of fluid ow in the circuit, a trip for holding said control lever in one extreme position for directing the fluid to move the platen towards the table, means responsive to the built up pressure in the circuit during said movement of the platen to release said trip, said responsive means including a pressure chamber operatively connected to the circuit, and a piston in said chamber and connected to the trip, and means for moving the control lever to the other extreme osition upon release of said trip whereby t e direction of fluid flow in the circuit will be reversed.

18. The combination with press includin a stationary table and a reciprocatory p aten movable towards and from the table, of a reversible pump, means forming with the press and pump a hydraulic circuit, controllmg means operatively connected with the pump and circuit for efi'ect-' ing movement of the. platen towards and from the table and including a control lever operatively connected with the ump for controlling the direction of fluid ow in the circuit, a trip for holding said lever in one extreme position for directing the fluid to move the platen towards the table, means responsive to the built up pressure in the circuit during said movement of the platen to release said trip, said responsive means including a pressure chamber operatively connected to, the circuit, and a piston in said chamber and connected to the trip, means for moving the-lever to the other extreme position upon release of said trip whereby,

the direction of fluid flow in the circuit will lever in one the other extreme posia hydraulic reverse movement thereof to automatically neutral 19. T e combination with a hydraulic;

termediate position for placing the pump in osltion.

press including a stationary table and a reciprocatory platen movable. towards and from the table, of a reversible pump, means forming-with the press and pump a hydraulic circuit, controlling. means operatively connected with the pump and circuit for effecting movement of the platen towards the table and responsive to the pressure built up in the circuit during said movement of the platen for automatically reversing the pump and the platen irrespective of the position of the platen relative to thetable, and means connected to the controlling means and operated by the platen during the reverse movement thereof to automatically place the pump in neutral position and thereby stop the movement of the platen at the end of one complete cycle.

20. The combination with, a hydraulic press including a stationary table and a reciprocatory platen, movable towards and from the table, of a reversible pump, means forming with the press and pump a hydraulic circuit, and controlling means operativel from the table and including a control lever operatively connected with the pump for controlling the direction of fluid flow in the connected with the pump and circuit for e fecting movement of the platen towards and circuit, a trip for holding said lever in one extreme position for directing the fluid to move the platen towards the table, means responsive to the built up pressure in the circuit during said movement of the platen to release said trip, and means for moving the control lever to the other extreme position upon release of said trip whereby the direction of fluid flow in the circuit will be reversed, and means connected to the control lever and operated by the platen during the move the lever to an intermediate position and thereby place the pump in neutral position and stop the movement of the platen at the 'end of one complete cycle.

.21. The combination with a hydraulic press including a stationary table and a reciprocatory platen movable towards and from the table, of a reversible pump, means forming with the press and pump a hydraulic circuit, and controlling means operatively connected with the pump and circuit for effecting movement of the platen towards and from the table and including a control lever operatively connected with the pump for controlling the direction of fluid flow in the circuit, a trip for holding said lever in one extreme position for directing the fluid to move the platen towards the table, means responsive to the built up pressure in the circuit during said movement of the platen to 'ciprocatory p release said-trip, and ineans for movingthe controllever to the other extreme position upon release of said trip whereby the dire'ction of fluid flow in the circuit will be reversed,fand means connected to the control .lever and operated by the platen during the reverse movement thereof to automatically move the lever to an'intermediate position and thereby place the pump in neutral position and sto the -movement of the platen at the end 0 one complete cycle, and manually operable means connected to the control lever for moving the same for engagement-t by the trip.

22. The combination with a hydraulic press including a stationary table and a reaten movable towards and from the table, of a reversible pump, means table and responsive to the pressure built up in the circuit during said movement of the platen for automatically reversing the pump and the platen irrespective of the position pf the platen relative to the table, and means for automatically bringing the platen to rest at the end of a. return stroke.

23. The combination with a hydraulic press including a stationary table and a reciprocatory platen movable towards and from the table, of a reversible pump, means forming with the press and pump a hydraulic circuit, controlling means operativel connected with the pump and circuit for e fecting movement of the platen towards the table and responsive to the pressure built up in the circuit during said movement of the platen for automatically reversing the pump and the'platen irrespective of the position of the platen relative to the table, and means operated by movement ofthe platen during a return stroke for automatically bringing.

the platen'to rest at the end of such stroke.

24. The combination with a double acting hydraulic motor including a table, and a reciprocatory ram movable towards and from the table; v E a reversible pump; means forming with the motor and pump a hydraulic circuit; and controlling means operatively connected with the pump and circuit for controlling the direction of flow of fluid in the circuit for eii'ecting working and return strokes of said ram, said controlling means including a device movable to two positions to respectively efiect workin and return strokes, and a, means for detaining said device in a position to effect a working stroke and being adapted to be actuated by pressure built up in said circuit for releasing said device to eflect reversal of the ump and of the ram and performance 0? a return stroke.

25. The combination with a double acting i i I a 1a,?

hydraulic motor including a table, and a reclprocatory ram movable towards and from the table; of a reversible pump; means form- Y ing .with the motor and pump a'hydraulic 5 circuit; controlling means operatively connected with the pump and circuit for con- .trolling the direction of flow of fluid in the circuit for efiecting working and return strokes of said ram, said controlling means including a device movable to two positions to respectively efi'ect working and return strokes, and a means for detaining, said device in a position to effect a worklng stroke and being adapted to beactuated by pressure built up in said circuit, for releasing said device to efi'ect reversal of the pump and of the ram and performance of a return stroke; and means operable when the ram approaches the end of a return stroke for bringing the ram to rest.

26. The combination with a double acting hydraulic motor including reciprocatory ram means, and cylinder means having ram-advancing and ram-returning chambers in which said ram means is mounted for performing working and return strokes, of a reversible pump; means forming with the pump and said ram-advancing and ram-returning chambers a hydraulic circuit; and

controlling means operatively connected with the pump and circuit for controlling the direction of discharge of said pump and the direction of movement of said ram means, said controlling means including mechanism movable to cause the pump to deliver fluid under pressure to said ram-advancing chamher to efl'ect a Working stroke of said ram means and being responsive to built up pressure in said ram-advancing chamber for au- 40 tomatically reversing the pump to deliver fluid under pressure to said ram-returning chamber'to thereby effect a return stroke or the ram means.

In testimony whereof I have hereunto subscribed my name.

- WALTER ERNST. l 

